Magnetic brake control



Sept. 20, 1938. E. E. HEwlTT MAGNETIC BRAKE CONTROL 3 Sheets-Sheet l Filed Jan. l5, 1937 Y SQ w\ K MQ.

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INVENTOR ELLE Hr-:WITT BY Qn d/ ATTORNEY MUS Sept. 20, 1938. E, E. HEWITT- MAGNETIC BRAKE CONTROL Filed rJan. 13, 1937 5 Sheets-Sheet 2 E. E. H EWITT MAGNETIC BRAKE CONTROL sept. 20, 193s.

Filed Jan. 13, 1957 3 Sheets-Sheet 3 V04 fas.

gllllllll NVNTOR ELLIS ETEWITT BY ATTORNEY Patented Sept. 20, 1938 UNITED sTATEs PATENT oFEicE IYIAGNE'IICl BRAKE CONTROL Application January 13, 1937, Serial No. 120,385

26 Claims.

This invention relates to magnetic brake control, and more particularly to brake equipment employing both fluid pressure operatedy brakes `and magnetic track brakes, in which the magnetic track brakes are controlled by and in relation to the application of the uid pressure brakes.

` With the advent of trains operating at unusually high speeds, as for example in the neighbor- `hood of one hundred miles per hour, the problem of stopping such trains in short distances becomes of first importance. The fundamental brake for such trains is the familiarflud pressure operated type of brake. As is well -understood, this brake comprises brake shoes operating upon the treads of the vehicle wheels. Due to the fact that the coeicient of friction between the brake shoes and the wheel treads is relatively low at high vehicle speeds and relatively high at low vehicle speeds, the braking force with which the brakes are initially applied is not as effective at the high speeds as at the low speeds. As a consequence, some difliculty may be experienced in obtaining the necessary braking at the high speeds. Moreover, if the brakes are applied to the maximum degree at a high speed, then as the speed of the vehicle diminishes, and the coefficient of friction between the brake shoes and wheel treads increases, the braking force must be reduced, or otherwise wheel sliding may result. In order to provide for adequate braking at the high speeds, it has heretofore been proposed to provide magnetic track brakes to augment the fluid pressure brakes. However, when making ordinary or service stops the fluid pressure brakes will in most cases be adequate, but in emergency cases, as when applying the brakes to avoid collision, additional braking may be required. It is therefore desirable that Where magnetic track brakes are provided as supplementary to the usual uid pressure brakes, the uid pressure brakes only be applied when effecting service the magnetic track brake devices remain energized excessive heating may result, and the windings of these devices may be burnt out. In order to avoid this it is desirable that the magnetic track brake devices be deenergized at or about the time the train is brought to a stop.

. With `the foregoing `considerations in mind, it

brakes are applied must be reduced as the vehicle Y speed diminishes, when a full application is made, or otherwise Wheel sliding may result. It` has heretofore been proposed to employ a retardation controllerV device, which operates responsive to the rate o f retardation of the train, to automatically reduce the braking force as the vehicle speed diminishes, and thereby minimize the danger of wheel sliding.

It is a further objecty of the present invention to provide a brake equipment of the type hereinbefore referred to, in which a retardation controller device is employed to control the uid pressure brakes, so as to minimize the danger of or prevent wheel sliding.

If aretardation controller device is provided it will be obvious that its adjustment should be different for emergency applications of the brakes than for service applications. That is to say, if the device is adjusted to limit the permissible rate of retardation to one maximum value for a service application, it should be adjusted to permit a higher maximum value during emergency applications. v Accordingly, therefore, it is a yet further object of the invention to provide a brake equipment of the type hereinbefore referred to employing a retardation controller device in which the adjustment of the `retardation controller device is automatically changed at the time the track brakes are applied, so as to permit a higher maximum rate of retardation than permissible during service applications.

It is also a further object of the invention to provide a brake equipment embodying the features set forth in the preceding objects, with the additional feature that when the track brakes are released (during an emergency application) the adjustment of the retardation controller device is reduced so as to permit the maximum rate of retardation normally permissible only for service applications of the brakes.

If in the type of brake equipments hereinbefore referred to, the track brakes are cut out of action an appreciable interval of time before the train is brought to a stop, the retardation controller device may fLuiction to increase the degree of application of the fluid pressure brakes. This may not be desirable in4 all cases, as the degree to which the fluid pressure brakes are applied at the time the track brakes are cut out of action may be fully adequate to bring the train to a stop promptly. I, therefore, contemplate, as a further object of the present invention, the provision of means in connection with brake equipments of the type hereinbefore referred to, wherein an increase in the degree of application of the fluid pressure brakes is prevented uponthe release of the track brakes before the train has been brought to a stop. That is to say, if the pressure of iiuid in the brake cylinder of the fiuid pressure brakes is at or above a given value at the time the track brake devices are deenergized, the then obtaining brake cylinder pressure cannot be increased before the train has been brought to rest.

In the most modern type of high speed trains, the propelling means comprises electric motors which receive electric power from an engine driven generator on the train. The engine which drives the generator is usually operated at some fairly high constant speed during the operation of the train. When the driving motors are disconnected from the generator, it is .customary to reduce the speed of the eng-ine to an idling speed. However, if the track brake devices are energized from the generator, as I contemplate doing, the engine speed should be maintained reasonably high. It is, therefore, a still further object of the invention to provide a brake equipment of the type hereinbefore referred to, in which upon disconnecting the driving motors from the generator and applying the magnetic track brakes, ameans is automatically operated to insure that the speed of the generator engine will be maintained high enough so that the track brake devices will be fully and sufficiently energized. Y

Other and more specific objects of the invention, dealing with the construction and arrangement of parts, Will be more fully understood from the following description of several embodiments of my invention, which description is taken in connection with-the attached drawings, wherein,

Fig. 1 shows in schematic and diagrammatic form an embodiment of my invention as adapted to the head end or controlcar of a high speed train. i

Fig. 2 illustrates in schematic and Adiagrammatic form a modification of the equipment shown in Fig. 1.

Fig. 3 is a fragmentary detail view of a portion of the retardation controller device shown centrally of Fig. 2.

Fig. 4 shows an alternative adjustment mechanism for that shown for the retardation controller device of Fig. 2.

Figs. 5 and 6 show in fragmentary form certain modications of the apparatus illustrated in Fig. 2.

Embodiment of Fig. 1

The embodiment of Fig. 1 has been illustrated in connection with a iiuid presure brake equipment rof the type described and claimed in the pending `application of Ellis E. Hewitt, Serial No. 741,063, filed August 21, 1934. The equipment as illustrated here has been, of course, greatly simplified.

As'shown, a brake cylinder is indicated at Il),

Vbustion engine 28.

an application and release magnet valve device at II, a master switch device at |2, a brake valve device at i3, an emergency valve device at |4, a retardation controller device at I5, a main reservoir at I6, and a feed valve device at To the fluid pressure brake equipment has been added a magnetic track brake equipment comprising one or more magnetic track brake devices 20, a track brake magnet valve device 2|, and an application and release relay 22. For timing the duration of application of the track brakes there is provided a timing relay 23.

Interlocking the magnetic track brake system and the liuid pressure brake system are two pneumatic switch devices 24 and 25.

For driving the control or head end car of the train, there is diagrammatically indicated a driving motor 26, which receives electric power from a generator diagrammatically indicated at 21, which generator is driven by an internal com- The supply of power from the generator 2l to the driving motor 26 is controlled by a motor controller device 23.

Considering now more in detail the devices and apparatus above enumerated, the application and release magnet valve device comprises an application valve 3G and a release valve 3|. The application valve 33 is urged toward seated position by a spring 32, and is actuated to unseated position upon energization of an electromagnet 33. Similarly, the release valve 3| is Yurged toward seated position by a spring 34, and is actuated to unseated position upon energization of an electromagnet 35.

When the application electromagnet 33 is deenergized and the release electromagnet 35 is energized, as shown, a communication is established between a straight air pipe 36 and the atmosphere, by way oi?` the now unseated release valve 3| and exhaust port 3l. When the release electromagent 35 -is deenergized and the application electromagnet 33 is energized, this communication to the atmosphere is closed, and communication is established between a supply reservoir 38 and the straight air pipe 35, by way of supply pipe 39, and past the now unseated application valve 30.

The master switch device I2 is embodied in a casing,preferably comprised of insulating material, as for example micarta. or bakelite, and i has centrally disposed therein `a fiexible diaphragm 42, which vhas connected thereto, on opposite sides thereof, two stems 43 and 44. The stem 43 is effective in operating release contacts 45, while the stem 44 is effective in operating application contactsli. The diaphragm 42 is so constructed and arranged that in its normal or unflexed state the release contacts 45 are maintained closed while the application contacts 46 are maintained open.

The diaphragm 42 is subject on its uppermost side to pressure of fluid in a-chamber 4'! and on its lowermost side to pressure of fluid in a chamber 48. The chamber 41 is connected to one section of a control pipe 5t, while the chamber 48 is connected to the aforementioned straight air pipe 36.

When fluid under pressure is supplied to the chamber 4'! the diaphragm 42 will be iiexed down- Wardly, whereupon contacts 45 will be opened and contacts 46 closed. When, subsequently, iiuid under pressure is supplied to the chamber 48, and the pressure in this chamber reaches a value slightly below the pressure in chamber 41, the

diaphragm 42 will be exed upwardly and there 75 by cause opening of contacts 46. If thepressure in `chamber 48 should appreciably exceed the pressure in chamber 41, the contacts will be then closed. However, if the pressure in chamber 48 remains slightly below the pressure in chamber 41 both sets of contacts 45 and 46 will remain open; I

The brake valve device I3 is preferably of the type illustrated in the aforementioned Hewitt application, Serial No. 741,063. For the purposes ofthe present disclosure, the brake valverdevice may be considered as having a handle 5I, which is movable out of a release position to any one of a plurality of positions in an application zone, and beyond said application zone to anemergency position. When the handle 5I is inthe release position, the control pipe 58 is connected to the atmosphere, and a brake pipe 52 is connected to a feed valve pipe 53. The feed valve pipe 53 is, as illustrated, connected to the feed valve device I1, which valve device is to be un,- derstood as being of conventional design, and functions to deliver fluid under pressure from the main reservoir I6 to the feed Valve pipe 53 at some substantially xed pressure.V

s When the brake valve handle 5I is moved out of release position to some position in the service application Zone, the communication between the control pipe`50 and the atmosphere is closed, and iiuid under pressure is supplied from the feed valve pipe 53 to the control pipe 50, to a degree dependent upon the extent of movement of the handle 5I into the service application zone. During this movement of the handle the brake pipe 52 remains in communication with the feed valve pipe.

`When the handle 5I ismoved tothe emergency position, uid under pressure is supp-lied to the control pipe 5I) to the. maximum possible degree, while communication between the brake pipe 52 and the feed valve pipe 53 is closed, and the brake pipe 52 is vented to the atmosphere at an` emergency rate. y

The emergency valve device `III is embodied in acasing having disposed therein a piston 55,

subject on one side to the pressure of fluid in a chamber 56 and on the other side of the pressure of fluid in a slide valve chamber 51. The slide valve chamber 51 is in vcommunication with a quick action chamber 58 by way of port 59. The piston is provided with a stem 66 which is recessed to receive and move coextensive with movement thereof 'a graduating valve 6l. The stern B0 is also provided with shoulders: 62 which are adapted to engage, after a lost motion move ment of the piston 55, a main slide valve 64.

`Also carried by the stem` 60 is a graduating stop 65, which is urged to the left by a spring 66. As will be observed, tension on the spring 66 may be adjusted bya nut 81. In a lower part of the Valve device casing is a vent valve 68, which is urgedtoward a seated position by a spring 56. Attached to the vent valve 58 is a piston 18, which is subject 'on its uppermost side to pressure of fluid in a chamber 1I, and on its lowermostside to pressure of fluid ina chamber 'I2A normally open to the atmosphere byl way of passage 13. Thepiston 15 "contains a small or restrictedport 14 therein providing Va restricted communication between the chambers 1I and12. Also,.there is provided `a restricted passage 15 in the bushing in which 4the piston moves, which establishes a communi-- cation around the piston when in the illustrated position. l .i

munication with a passage 31.

Considering now the operation of the emergency valve device I4, the chamber 56, to the left of piston 55, is connected to the brake pipe 52, and when the piston is in the illustrated position a feed groove 16 provides communication between the chamber 56 and the slide valve chamber 51 and quick action chamber 58. With the brake pipe 52 fully charged, and piston 55 in the illustrated position, all of these charnbers will be charged `to brake pipe pressure.

When a reduction in brake pipe pressure is effected at a service rate (not of practical importance here, but of importance in a practical brake system of the type illustrated in the aforementioned Hewittapplication), the overbalancing pressure of fluid in chambers 51 and 58 will cause the piston 55 Yto move to the left, closing the feed groove 16. As the piston closes: the feed groove,A the graduating stop 85 engages the right end of the main slide valve 64, and tends to arrest further movement of the piston. At this point a small port 18 in the graduating valve 6I is brought into registration with a port 19 `in the main slide valve, which at this time is open to an exhaust port 85. Fluid under pressure will then flow fro-m the chambers 51 and 58 to the atmosphere. The size of the port 18 is made such that the pressure in chambers 51 and 58 will reduce at substantially the same rate as the pressure reduces in the chamber 56, due tothe reduction of pressure in the brake pipe at a service rate.- Therefore, when the full reduction in brake pipe'pressure` has been effected, the piston 55` will move back to the illustrated position, whereit 'will remain if no further reduction in brake pipe pressure takes place.

If, however, the pressure in the brake pipe 52 is initially, or subsequently, reduced at an emergncy rate, the greatly overbalancing pressure in the chambers 51 and 58 will cause the piston 55 to move outwardly and compress the spring 66 behind the stop 65. The graduating valve 6I will bethen shifted such thata port 8| inthe main slide valve is uncovered, which port at this time is in registration with a passage 82 leading to the piston chamber 1I. Fluid under pressure will then flow from the chambers 51 and 58 to the piston chamber 1I. This flow is intended to takeyplace rapidly enough to move the piston 16 downwardly, and thereby unseat the vent valve 68. l

Unseati-ng of the vent valve opens communication between the brake pipe '52 and the eX- haust passage 13, so that there is immediately produced a sharp dropin brake pipe pressure, which of course occurs adjacent each emergency valve device where there is such a device on each car-in the train. This sharp drop in brake pipe pressure at each emergency valve device will cause `the piston 55 in each device to be moved kto its extreme left hand position, where the main slide valve 64 uncovers.` the passage 82, and where exhaust port 88 is blanked by the main slide valve, In addition, the main slide valve interrupts communication between two passages 85, which two passagesconnect, respectively, with the two adjacent sections of the control pipe 56, and which were previously connected together by cavity 85 in the main slide valve. A port 85 in the main slide valve is in the extreme left hand position of the piston 55 brought into com- Since the port 86 is also incommunication with the cavity 85,

which at this time connects the left hand passage 84 Awith a `passage 88 vleading to the feed valve pipe 53, it follows that fluid under pressure can ow from the feed valve pipe 53 to both the left hand passage 84 and to the passage 81.

With the chambers-51 and 58 open to the piston chamber 1|, the pressure in these chambers will be exhausted after a predetermined length of time, due to the presence of the restricted port 14 in the piston 10. However, this will not take place until after the pressure inthe brake pipe will have been substantially depleted, so that the parts of the emergency valve device, that is, the main slide valve 64 and piston '55, will remain in the extreme left hand position.

Upon a restoration of pressure in the brake pipe 52, the piston 55 will move back to the illustrated position, carrying with it the graduating valve 6| and main slide valve 64, to reestablish the communications as illustrated in Fig.` 1.

Considering now the retardation controller device |5, this device is preferablyembodied in a casing having disposed therein a body 90 provided with anges or wings 9| which roll upon rollers 92 carried by the casing. At one end of the body 90 is disposed a lever 93, which is pivotally mounted upon a pin or rod 94 carried by the casing. The lever 93 is bifurcated at its upper end and carries between the bifurcations a roller 95 which engages one end of the body 90. The lever 93 is also bifurcated at its lower end, and carries between `the bifurcations there a second roller 96 which engages one end of a slide valve 91. The slide valve 91 is operable in the illustrated position to connect two adjacent sections of the control pipe 50. YAt the opposite end of the slide valve 91 is disposed a spring 98.' This spring biases the.` slide valve to the illustrated position, and as a consequence holds the body 90 against a stop 99. i Y The retardation controller device is preferably positioned upon the vehicle such that when the vehicle is deceleratingv the resultant force of inertia acts to urge the body 90 to the left. As the body 90 moves to the left it shiftsV the slide valve 91 to the right,` against opposition of the spring 98. The spring 98 is a calibrated spring, so that vthe degree to which the slide valve 91 is shifted is proportional to the rate of deceleration of the vehicle. When the body 90 has been moved under a force of inertia corresponding to a predetermined rate of retardation, the slide valve 91 will have been shifted to a position where it blanks the left hand section of the control pipe 50. At a higher rate of retardation the slide valve 91 will be shifted to the position where the right hand section of the control pipe 50 will be connected to an exhaust port |09. The rates of retardation required to shift the slide valve, as just described, may be varied by varying the tension on the spring 98. For accomplishing this there is provided all adjusting mechanism comprising a cylinder in which is disposed a piston |02. Attached Ato the piston |02 is a stem |03, one `end of which is loosely attached to one end of a lever |04 pivotally mounted at |05` to the casing. The other end of the lever engages a stop |06 on the stem of an abutment 08 which presses against the spring 98. The cylinder |0| is connected to the brake pipe 52, and so long as the brake pipe is charged the piston |02 is biased to the left, thereby placing a minimum tension on the spring 98. ,Upon a reduction of pressure in the brake pipe 52 to effect an emergency application of the brakes, a spring .|01 tothe left of the piston |02 forces the piston to its extreme right hand position, and thereby places additional tension on the spring 93. The retardation controller device is thus adjusted to permit a higher rate of retardation during emergency applications of the brakes.

Considering now the magnetic track brake equipment, the track brake device 20 may be of any of the conventional types, which has projecting upwardly therefrom a lug ||0, to which is secured one arm of a bell crank lever The bell crank lever is preferably pivotally mounted at 2 to some portion of the vehicle truck. The other arm of the bell crank lever is connected to the stem of a piston 3 disposed in a raising cylinder ||4. So long as fluid pressure is maintained in the raising cylinder ||4, the piston ||3 will be biased to the left and cause the track brake device 20 to be held suspended above the track rail. When fluid under pressure is released from the raising cylinder H4, the track brake device 20 will drop to engagement with the rail under the force of gravity.

The track brake magnet valve device 2| is embodied in a casing having disposed therein a double beat valve |l5, which is urged toward an upper seated position by a spring H6. An electromagnet `|1 in the upper part of the valve device casing functions when energized to shift the `double beat `valve l5 to lower seated position. When the double beat valve I5 is in upper seated position, as shown, a communication is established between the sup-ply reservoir pipe 39 and the cylinder ||4. When the double beat valve is in lower seated position this communication is closed, andthe cylinder ||4 is vented to the atmosphere by way of exhaust port I8.

The application and release relay 22 comprises a winding or solenoid |20, which is operable when energized to actuate upwardly a stem |2|. Carried by and insulated from the stem |2| are two contact members |22 and |23. When the winding |20 is deenergized the Contact members |22 and |23 are positioned as shown, but when the winding is energized the contact member |22 engages stationary contacts |24 while the contact member |23 engages stationary contacts |25. This relay is preferably of the slow release type, for a reason which will be apparent later.

The timing relay 23 comprises a winding |26 which is effective When energized to actuate upwardly a stem |21. 'The stem |21 carries insulated therefrom a contact member |28 which is operable when the stem is actuated upwardly to engage' two stationary contacts |29.

'I'he two pneumatic switch devices 24 and 25 comprise essential like parts, each being embodied in a casing having contained therein a piston |30, which is biased to a lower portion by a spring |3|. Attached to the piston is a stem |32 which carries insulated therefrom a contact member |33.v Contact member |33 is adapted `to engage stationary contacts |34. As will be observed, in the case of the switch device 24 the contact member |33 engages contacts |34 when the piston |30 is in the lower position, and in the case of the switch device 25 the contact member |33 engages the contacts |34 for the upper position of the piston.

Both pneumatic switch devices 24 and 25 are connected to a pipe |35 which leads to the passage 81 in the emergency valve device |4. 'Iherefore, when fluid under pressure is supplied to the passage 81 it flows to both switch devices.

The vehicle driving motor 26 has been indicated in diagrammatic form only as representative of a number of such motors which may be employed.

l Similarly, the engine 28 has been indicated diagrammatically only and may be considered as having a carburetor, or other fuel feeding device, |36, which is operated upon movement of a throttle |31. Attached to the throttle |31 is a rod or stem |38, which is operable by a hand lever |39. The hand lever |39 mayhave an idling position and several operating positions as indicated by the numerals I and 2.

Secured to the rod or stem |38 is a highly magnetic member |48, as a soft piece of iron or steel, and concentrically disposed with respect to this member is a solenoid |4I. The purpose of this arrangement will be more fully hereinafter described.

The motor controller 29 may be considered to be of conventional design, as the details of this device are not an essential part of the present invention. The motor controller is preferably provided with a handle |42 for operation thereof.

The operation of this embodiment of my invention is as follows: i

Running condition When the vehicle is running under power the brake valve handle 5| is maintained in the release position. In this position of the handle, as before described, the control pipe 50 is in communication with the'atmosphere, and the brake pipe 52 is maintained charged from the feed valve pipe 53. Fluid under pressure in the brake pipe 52 flows to the chamber 55 in the emergency valve 1 device I4, and by way of the feed groove 16 to the slide valve chamber 51 and quick action chamber 58. Fluid under pressure in the brake pipe also flows to the chamber below the vent valve 68, and to the cylinder I|II on the retardation controller device I5.

At the same time, fluid under pressure flows to the supply reservoir 38 by way of one-way check valve device |43. The system is, therefore, charged and ready for operation.

While the vehicle is in operation the engine operating handle |39 is preferably turned to one of the operating positions, as illustrated. The engine 28 is, therefore, driven at an operating speed. The motor controller 29 is then operated to supply power from the generator 2l to the driving motor 25, to drive the vehicle at the desired speed. i

With the control pipe 58 maintained connected to the atmosphere, the fluid pressure brakes will be maintained fully released. At the same time,

fluid under pressure will be supplied from the supply reservoir 38 to the track brake raising cylinder II4, so as to hold the track brake device 28 suspended above the track rail. The application and release relay 22 will be deenergized, so that the winding of the track brake device will also be deenergized.

Service applications of the brakes When it is desired to eifect a service application of the brakes, the motor controller handle |42 is thrown to the off position, and the brake valve handle 5I is turned to a position in the service application zone. Fluid under pressure will be then supplied to the control pipe 50 to a degree corresponding to the position of the brake valve handle in the service application zone. Fluid under pressure supplied to the control pipe 50 ows to the chamber 4'I in the master switch device I2, by way of a iirst section munication with the switch chamber 4l.

of the control pipe 58, passages 84 and cavity 85 in the emergency valve device I4, a second section of the control pipe 5U, through the retardation controller device I5, and a third section of the control pipe 5I). The diaphragm 42 will then be flexed downwardly to open the release contacts 45 and close the application contacts 46.

When the release contacts 45 were closed, they established a circuit between a battery 45 and a release train wire |48, which circuit included conductor I 41, the release contacts 45, and the train conductor |48. Energization of the train conductor |45 maintainedA the release electromagnet 3,5 in each application release magnet valve device I I energized, and when the contacts` 45 are opened this electromagnet will be deenergized, whereupon the release valve 3| will be seated by its spring 34.

When contacts 45 are closed, a circuit is established from the battery |45 to an application train wire |48, whereupon the application electromagnet 33 in each valve device II will be energized to unseat supply valve 88. Fluid under pressure will then flow from the supply reservoir 38 to the straight air pipe 36, and consequently to the brake cylinder I8 and to the chamber .48 in the master switch device I 2.

When the pressure in the chamber 48 and brake cylinder I is slightly below the pressure in chamber 4l the diaphragm 42 will ileX upwardly and open the application contacts 45, while at the same time holding the release contacts 45 open. This will deenergize the application electromagnet 33 in each valve device II, and thereby lap the supply of fluid under pressure to the straight air pipe 36 and brake cylinder I8. The degree of brake cylinder pressure will then correspond to the position of the brake valve handle in the application zone.

The magnetic track brakes are not applied for a service application of the brakes, as the emergency valve device I4 must be operated to effect the operation of the track brake system, and since during a service application the brake pipe 52 is maintained charged, no operation of the track brake system takes place.

As the train begins to decelerate due to application of the fluid pressure brakes, the resulting force of inertia urges the body 98 of the retardation controller device to the left. It will be observed that the tension on the spring 98 at this time is a minimum, because with the brake pipe charged the pressure in the adjusting cylinder IBI is maintained at brake pipe pressure.

If now the rate of retardation should reach a value such that the slide valve 91 is shifted to blank the communication to the third section of the control pipe 50, it will be apparent that the brake valve device I3 willbe isolated from com- If the rate of retardation should increase to the point where the slide valve 9'! opens communication between the third section of the control pipe 50 and the atmospheric port |80, fluid under pressure will be released from the switch chamber 41. Upon release of uid under pressure from the chamber 4l, the diaphragm 42 exes upwardly and closes the release contacts 45. sult in energizing the release electromagnet 35 in each valve device Il, whereupon due to the unseating of the release valve 3| fluid under pressure will be released from the straight air pipe 36 and brake cylinder I8.

With the resulting decrease in the degree of application of the brakes, the rate of retardation This will rewill diminish and the body 90 will move toward the right. The slide valve 91 will move to the left and terminate the release of fluid under pressure from the switch chamber 41. When the pressure in the chamber 48 attains a value slightly less than that in chamber 41 the application will again be lapped.

A little thought will show that the retardation controller device will cycle, or will move between lap and release positions, as the speed of the train diminishes and the resulting braking effect increases due to the increase in the coeiiicient of friction between the brake shoes and wheel treads.

' That is to say, the retardation controller device |28 to engage the contacts |29.

will function to continually reduce brake cylinder pressure when the increase in coeflicient of friction tends to increase the ultimate braking effect. At any time it is desired to release the brakes, this may be accomplished by returning the handle 5| to release position. This will result in a decrease o'f pressure in the switch chamber 41, and thereby cause a like decrease of pressure in the straight air pipe 36 and brake cylinder l0. If at the time such a release is desired, the slide valve 91 in the retardation controller device has interrupted communication to the third section of the control pipe 50, the release will be accomplished by the unseating of the check valve |49, which will open a one-way communication between the third and second sections of the control pipe.

Emergency applications of the brakes When it is desired to effect an emergency application of the brakes, the brake valve handle 5| is turned to the emergency position, whereupon fluid under pressure is supplied to the control pipe 59 to the maximum degree, and at the same time fluid under pressure is released from the brake pipe 52 to the atmosphere at an emergency rate. As before described, the emergency valve device |4 responds and shifts its main slide valve 64 to the extreme left hand position. The main slide valve then opens communication between the passage 88 and each of the passages 81 and the left hand passage 84, while blanking the right hand passage 84. Fluid at feed valve pressure then flows through the second section of the control pipe 59 and from thence to the switch chamber 41, and also by Way of pipe |35 to each of the pneumatic switch devices 24 and 25.

Fluid under pressure supplied to the switch chamber 41 will effect the operation of the application and release magnet valve devices I as before described for a service application of the brakes.

Fluid under pressure supplied to the pneumatic switch device 24 will cause the contact member l 33 thereof to disengage from the stationary contacts |34, and thus open the circuit to the driving motors, in case this has not already been done by movement of the controller handle |42 to the off position.

Fluid under pressure supplied to the pneumatic switch device 25 will cause its contact member |33 to engage the stationary contacts |34. Ihis will connect the timing relayr23 to the driving motor 26, which will now operate as a generator and will energize the relay winding |26. The relay 23 will then quickly cause its contact member This will in turn energize the application and release relay winding from the battery |45. The application and release relay will then quickly cause contacts |22 to engage contacts |24, and contact |23 to engage contacts |25.

When contact |22 engages contacts |24, the battery |45 is connected to a train Wire |5|, and thereby energizes the electromagnet ||1 of each track brake magnet valve device 2|. This will result in lowering of each track brake device 20 intoengagement with the track rail. At the same time, engagement of relay contact |23 with contacts |25 establishes a circuit from the generator 21 to the track brake device, by way of conductor |52, and at the same time energizing train conductor |53 so as to energize all of the track brake devices throughout the train. The track brakes will thus be fully applied.

When the timing relay contacts |28 and |29 engage, the solenoid |4| is energized, by way of conductor |54. The purpose of energizing this solenoid is to insure that the engine 28 is kept running at a speed high enough for the generator 21 to deliver suiicient energy for the track brake devices. driving motors the hand lever |39 is maintained in a running position. When, however, the supply of energy to the driving motors is cut off, it is customary to move the hand lever |39, either manually or automatically, to an idling position, so as to not waste engine fuel needlessly.

When the solenoid |44 is energized the core |48 is attracted inwardly thereof, regardless of to which side of the solenoid the core happens to be initially, and when the core comes to rest centrally of the solenoid the engine throttle |31 will be in a position to operate the engine and generator at a speed suiciently high to meet the requirements of the track brake-devices, and yet at a speed which is economical.

When the pressure in the brake pipe is reduced at an emergency rate, the piston |02 in the retardation controller adjusting mechanism moves to its extreme right hand position, and the tension on the spring 9S is increased, as before described. The retardation controller is thus adjusted to permit a higher maximum rate of retardation, and the retardation controller device will function as before described for a service application of the brakes to control the uid pressure brakes only. The total braking produced will, of course, be that due to the joint and concurrent application of both the magnetic track brakes and the fluid pressure brakes, but the track brakes remain applied to a degree according to the initial energization of the track brake devices, whereas the brake cylinder pressure in the fluid pressure brakes is modified as is necessary to cause the train to be decelerated at a rate of retardation not exceeding that according to the adjustment of the retardation controller device.

As the speed of the train diminishes to some low value, at or near the end of the deceleration period, the voltage delivered by the driving motor '2li will be insuilicient to maintain the timing relay 23 energized. This relay will then open its contacts |29 and deenergize the application and release relay 22, which, due to its slow release action, opens its contacts `after a slight delay. This will result in a complete release of the magnetic track brakes.

At the same tim-e, deenergization of the timing relay 23 deenergizes the solenoid |4|, so that the engine speed may be adjusted, either by automatic means or by manual manipulation of the handle |39. The delay provided by relay 22 permits the track brake devices to be deenergized vat the low engine speed, which reduces contact arcing and danger of high induced voltage.

The train will then be brought to a stop due to When energy is being'supplied to the application of fluid pressure brakes only, and when it is desired to release the brakes', the brake valve handle 5| is returned to the release position, whereupon the brake pipe 52 will again be charged to normal value. With recharging of the brake pipe the parts of the emergency valve device I4 will move to the illustrated position, and release of fluid under pressure from the switch chamber 41 will take place to the atmosphere through 'the communication established in the brake valve device I3. A full release of the iluid pressure brakes will then result in the same manner as described for a release following a service application.

Modification shown in Fig. 2

The embodiment of Fig. 2 deals with the substitution of certain devices for some of the devices shown in Fig. 1.

In Fig. 2, a retardation controller device of the electric type, shown at |56, and its cut oil and release magnet valve device |51, have' been substituted for the pneumatic type retardation controller device I5 of Fig. 1. As will be observed,

the magnet valve device |51 has been disposed in the control pipe 5D between the emergency valve device i4 and the master switch device I2, as was the retardation controller I5.

Also in Fig. 2, a pneumatic switch device |58 and a relay |59 replace the pneumatic switch device and the application and release relay 22 of Fig. 1. The pneumatic switch device 2li of Fig. l may be still retained in the motor circuit, which has been omitted in Fig. 2.

The timing relay 23 oi Fig. 1 has been replaced in Fig. 2 by a speed controlled switch device |66, together with a relay |6|.

The adjusting cylinder |0I for the retardation controller device of Fig. 1, has now been replaced by that provided on the new retardation controller |56, together with an adjusting magnet valve device |62.

As will be observed from the arrangement shown in Fig. 2, the new parts are connected in the system of Fig. 1 to the pipes and circuits of that system as indicated by the like use of numerals.

Considering now more in detail the new devices of Fig. 2, the retardation controller device |56 is embodied in a casing having pivotally mounted therein a pendulum |64, suspended at |65, and carrying insulated therefrom a contact |66. The pendulum |54 is biased to the illustrated position by a calibrated spring |61 acting upon a plunger |68 in engagement with the pendulum. VIn the illustrated position of the pendulum, the Contact |66 engages two resilient stationary contacts |69 and |18.

As in the case of the retardation controller device |5, the pendulum |64 is movable to the left, upon deceleration of the vehicle, a distance proportional to the rate of deceleration, against opposition of the calibrated spring |61. Tension on the spring |61 is governed by an adjusting mechanism comprising an arm |1| pivotally mounted at |12 to the casing and having a limited movementbetween stops |13. The free end of the arm I1I engages an abutment |14 in contact with the spring |61, while intermediate its ends the arm I1| is connected by a stem |15 to a piston |16 disposed in a chamber |11. The piston |16 is urged to the right by a spring |18.

When the pressure in chamber |11 is at atmospheric pressure, the spring |18 biases the arm |1| to its inner position, in which case the initial tension on the calibrated spring |61 is a maximum. When fluid under pressure is supplied to the chamber |11 to a degree suicient to compress the spring |18, the arm I1I is actuated outwardly until it engages the outermost stop |13, as illustrated, whereupon the initial tension on the calibrated spring |61 is a minimum.

The adjusting magnet valve device |62 controls the supply of fluid under pressure to and its release from the chamber |11. This magnet valve device'comprises a double beat valve |86 which is urged toward an upper seated position by a spring I8|, and is actuated to lower seated position upon energization of an electromagn-et |82. When the double beat valve |86 is in the upper seated position, as illustrated, the chamber |11 is connected to the supply reservoir pipe 39. When the double beat valve is actuated to the lower seated position, this communication is closed and a communication is opened between the chamber |11 and atmospheric port |83, so that fluid under pressure will be released from the chamber |11 to the atmosphere.

The cut-oilc and release magnet valve device |51 comprises a cut-off valve |85 and a release valve |86. The cut-off valve |85 is urged toward seated position by a spring |81, and is actuated to unseated position upon energization of an electromagnet |88. The release valve |86 is urged toward unseated position by a spring |89, and is actuated to seated position upon energization of an electromagnet |90.

When the release valve |86 is seated and the cut-ofi valve |85 is unseated, as illustrated, the two sections of the control pipe 58 are in open communication. When the cut-off valve is seated this communication is closed, and when at the same time the release valve |86 is unseated, the third section of the control pipe 50, that is, the section leading to the master switch device I2, is opened to the atmosphere by way of exhaust port |9I.

The pneumatic switch device |58 is embodied in a casing comprising a piston |92 subject on one side to the pressure of fluid in a chamber |93 and on the other side to the pressure of a spring |94. Secured to the piston |92 is a stem |95 which carries insulated therefrom, and from each other, two contact members |96 and |91, the former being adapted to engage stationary contacts. |98 and the latter being adapted to engage stationary contacts |99.

The speed controlled switch device |68 comprises a movable contact 266 which is adapted to engage stationary contacts 26|. contact 286 is carried by and insulated from a stem 292, which is urged downwardly by a spring 283 acting between a portion 284 of the casing and a collar or washer 265 secured to the stem 202.

The stem 262 is actuated upwardly due to the centrifugal action of two'y ball weights 286, which are pivotally mounted at 291 to a rotatable member 298. The rotatable member 288 is driven by a shaft 299, which rotates at a speed corresponding to the speed of the train, as by coupling to a vehicle wheel, or axle, or some other part which rotates at a speed corresponding to train speed.

The relay |6| comprises a winding or solenoid 2|B which when energized attracts upwardly a core 2| I to which is secured, and insulated therefrom, a movable contact 2|2, which then disengages from stationary contacts 2 I3. When the winding 2| e is deenergized the movable contact The movable 212 drops by gravity to engagement with the contacts 2|3.

The relay |59 is similar to the relay IBI, comprising a winding or solenoid 2|4, which when energized attracts upwardly a core 255 having attached thereto and insulated therefrom a movable contact 2|6, adapted in its uppermost position to engage stationary contacts 2|1. When the winding 2H is deenergized the core member 215 drops downwardly under the force of gravity, whereupon contact E i6 disengages from contacts In the operation of the brake system with the modications shown'in Fig. 2, the system is charged as before described for the embodiment of Fig. l. The pneumatic switch device |58 is connected to the brake pipe 52, as illustrated, and so long as the brake pipe is charged the piston 92 will be actuated upwardly so that contacts |91 and |96 are out of engagement with contacts |99 and |68, respectively.

. Assuming that the train is traveling at some fairly high speed, theparts of the speed con.- trolled switch device |66 will be in the positions as illustra-ted. With the contacts of the speed controlled switch device in open position, the other parts connected thereto will be also in the positions as illustrated.

When now upon effecting a service application of the brakes fluid under pressure issupplied to the control pipe 56, it will flow to the master switch device I2, through the cut ofi and release magnet valve device |51, and will as before described in connection with the embodiment of Fig. 1 effect an application of the fluid pressure brakes, the degree of the application depending upon the degree of movement of the brake valve handle 5| into the service application zone.

As will be observed, the adjusting magnet valve device |62 is deenergized for the condition assumed, so that the double beat valve |66 is in upper seated position, and fluid at supply reservoir pressure is delivered to the chamber |11. As a consequence, the minimum initial tension existsl on the adjusting spring |61.

Assuming now'that the rate of retardation of the train increases suiciently to actuate the pendulum 64 to the position illustrated in Fig. 3. the circuit tol the cut off electromagnet k|85 will be interrupted, and the cut-off valve |85 will be.

actuated to seated position by the spring |81. This isolates the brake valve device I3 from the master switch device I2 and prevents further supply of iluid under pressure to the switch chamber 41. If the rate of retardation increases further, so that the pendulum contact |66 disengages from the stationary conta-ct |10, then the release electromagnet |96 will be deenergized, and release valve |86 will move to unseated position to release uid under pressure from the switch Chamber 41 to the atmosphere, by way of ex- When the rate of retardation has diminished sufliciently for contact to reengage contact |16, the release will be terminated.

It will thus be observed that the retardation controller device |56, together with its magnet valve device |51, perform all of the functions of the pneumatic type retardation controller device I5 Yof Fig. 1.

When it is desired to release the brakes, the brake valve handle 5| is returned to release position, whereupon fluid under pressure is released from the switch chamber 41, the check valve 2|8 in the magnet valve device |51 unseating in the event that the cut-orf valve |85 is seated at the time the release is made.

When it is desired to effect an emergency application of the brakes, the brake valve handle 5| is turned to the emergency position to reduce brake pipe pressure at an emergency rate.

As before described in connection with the embodiment of Fig. l, the emergency valve device I4 will function to supply iluid under pressure to the control pipe 56 and master switch device l2 to the maximum degree, to effect a maximum application of the fluid pressure brakes. At the same time, the release oi fluid under pressure from the brake pipe 52 causes contacts |91 and |96 of the pneumatic switch device |58 to engage, respectively,.contacts |99 and |98.

Engagement of contacts |91 and |99 establishes a circuit from the battery |45 to the relay winding 2|4, of relay |59, and also to the track brake magnet valve device 2|. The magnet valve device 2| will effect the lowering of the track brake device 2|] to engagement with the rail, while the engagement of contacts 2|6 and 2|1 of the relay |59 will supply electric power from the generator 21 to the energizing windings of the track brake device 26. The track brakes will then be fully applied.

The engagement of contact |96 with contacts |98 of the pneumatic switch device |58 completes a circuit to and energizes the electromagnet |82 of the adjusting magnet valve device |62. As a consequence, the double beat valve |86 is shifted to lower seated position to close communication between the chamber |11 and the supply reservoir, and to` open chamber |11 to the atmosphere. As a result the maximum initial tension will be placed on the adjusting spring |61, so that the retardation controller device will be set to permit a higher rate of retardation.

The retardation controlled device will then operate substantially as heretofore described, except that it will permit a higher rate of retardation than for a service application.

When the speed of the train has diminished to a very low speed, as for example five or six miles per hour, the contacts 206 and 26| of the speed controlled switch device |60 will close, thereby energizing the relay |6|. This relay will then open its contacts 2|2 and 2|3, and thereby deenergize both the relay |59 and the adjusting magnet valve device |62.

Deenergization of the relay |59 completely releases the track brakes, while deenergization of the adjusting magnet valve device |62 results in changing the setting of the retardation controller l.

Modification shown in Fig. 4

The modification shown in Fig. 4 deals merely with the adjusting mechanism of the retardation controller device |56 of Fig. 2. In Fig. 2 the adjusting magnet valve device |62 is shown of the type which supplies fluid under pressure to the chamber |11 when the electromagnet |82 is deenergized. In case it is desired to employ the type of magnetvalve device, which connects the chamber to the atmosphere when the electromagnet |82 is deenergized, the adjusting mechanism must be arranged as in'Fig. 4, wherein it will be noted that the'piston |16 is connected to the end of the lever lll, instead of between'the ends. With these changes the retardation controller device will function the sameY as described in connection with the modification of Fig. 2.

Modification shown in Fig.

This modification deals with a rearrangement of the devicesv shownin Fig. 2, with the omission of,l the adjusting mechanism of the retardation controller device |56, and also omission of theadjusting magnet valve device |62. With the omission of these devices, there is added va pneumatic switch device 226, a volume reservoir 22|, a oneway check valve device 222, and a choke or restriction 223 in parallel with the one-,way check valve device.

`The purpose of this arrangement is to prevent an increase in whatever brake cylinder pressure exists at the time the track brakes are released near the end of the stop, during an emergency application of` the brakes.

The pneumatic switch device 226 is embodied in a casing containing a piston 224 urged to the right by a spring 225, and adapted upon supply of fluid under pressure to a chamber 226 to cause engagement of contacts221 and 228.

When an emergency application of the brakes has been effected, and contacts |96 and |98 of the pneumatic switch device |58 have closed, a circuit is potentially establishedto the cut oir electromagnet |88, in the magnet valve device |51, except .that itis dependent upon the closing of the contacts 22T and 228. These contacts close when the brake cylinder pressure has vattained a predetermined value. I'hat is to say, when brake `of the switch device 220, so that no further increase in fluid pressure in the brake cylinder I0 and straight air pipe 36 can take place, and the train will, therefore, be brought to a stop with whatever brake cylinder pressure is permitted below this predetermined value by the retardationk controller device |56.

`The `purpose of the choke` 228 and the volume reservoir 2|is to delay operation of the switch device` 226 for a sufcientinterval of time, so that routine yard tests can be made on the brake equipment while the train is at rest, without the interference with these tests by the operation of the. switch device220. Thedelay occasioned by the operation of the switch device 220 is of no consequence in the normal functioning of the apparatus during an emergency application of the brakes.

e Modification shown iii Fig. 6

` `The modification shown inFig. 6 deals with the rearrangement of the parts of the speed controlled switch device |66 shown in Fig. 2.

In Fig. 2, the contacts 200 and 20| of the speed controlled switch device |60 were shown as being held` open above a certain .predetermined vehicle or train speed, whereas in Fig. 6 the contacts have been so arranged as` to be Vheld closed above said predetermined speed and opened therebelow. That is. to.say,.the relay |59 will be energized at all times above said predetermined speed, and its contacts 2|6 and 2|`| have been rearranged so as tobe maintained open when the relay is energized, and closed when the relay is deenergized upon opening of contacts 200 and 20| below the predetermined speed. In all other respects the apparatus will function substantially as described for Fig. 2.

While I have described my invention with particular reference to one specic embodiment thereof, and several modifications of this embodiment, it is not my intention to be limited to the exact details shown, nor otherwise than by the spirit and scope of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is: n

l. In a vehicle or train brake system, in combination, a uid pressure brake system, a magnetic track brake system, control means operative when effecting a service application of the brakes to effect the operation of one of said brake systems only, and when effecting an emergency application of the brakes to effect the concurrent operation of both of said systems, a retardation controller device operable to control the operation of one of said brake systems only to limit the rate of retardation of the train to a predetermined value, and means automatically operable when effecting an emergency application of Vthe brakes to adjust said retardation controller device to permit a higher rate of retardation of the train than said predetermined value.

2. Inartrain brake system, in combination, a fluid pressure `brake system, a magnetic track brake system, control means` operative when effecting a service application of the brakes to effect the operation of said uid pressure brake system only and operable when effecting an emergency application of Vthe brakes to effect the operation of both said fluid pressure brake system and said magnetic track brake system, a retardation controller device operated according to the rate of retardation of the train, and being normally adjusted to limit the rate of retardation to a predetermined value, means responsive tothe operation of said retardation controller device for controlling the operation of said fluid pressure brake system only, and means operable when effecting an emergency application of the brakes for adjusting said retardation controller device to permit a. rate of retardation higher than said predetermined rate.

3. In a vehicle brake system, in combination, a

brake cylinder, a magnetic track brake device, j

control `means operative in effecting a service application of the brakes to effect only a supply of fluid under pressure to said brake cylinder, and operative when effecting an emergency application of the brakes to effect a supply of fluid under pressure to said brake cylinder and concurrently therewith to energize said track brake device, a retardation controller device operable to control brake cylinder pressure, and being normally adjusted to limit the rate of retardation of the vehicle to a predetermined rate, and means operable when effecting an emergency application of the brakes for adjusting said retardation controller device to permit a higher rate of retardation than said predetermined rate.

4. In la vehicle brake system, in combination, a brake cylinder, a magnetic track brake device, straight air means for effecting a supply of fluid under pressureto said brake cylinder, automatic means including a brake pipe and operable upon a reduction of pressure in said brake pipe to effect a supply of fluid under pressure to said brake cylinder and the energization of said track brake device, a retardation controller device operable to control brake cylinder pressure and being normally adjusted to limit the rate of retardation of the vehicle to a predetermined value, and means operable upon a reduction of pressure in said brake pipe for adjusting said retardation controller device to permit a higher rate of re'- tardation than said predetermined rate.

5. In a vehicle brakev system, in combination, a brake cylinder, a magnetic track brake device, straight air means for effecting a supply of fluid under pressure to said brake cylinder to effect a service application of the brakes, automatic means including a brake pipe and operable upon a reduction of pressure in said brake pipe at an emergency rate to effect an emergency application of the brakes, means also operative uponan emergency reduction in brake pipe pressure for effecting the energization of said track brake device and engagement thereof with a track rail to produce a track braking effect, a retardation controller device operative to control brake cylinder pressure, and means also operative upon the said reduction in brake pipe pressure for increasing the setting of said retardation controller device.

6. In a vehicle brake system, in combination, a fluid pressure brake system, a magnetic` track brake system, straight air means operative to effect the operation of said fluid pressure brake system to effect an application of the fluid pressure brakes, automatic means for effecting the operation of both of said brake systems to effect an application of both the fluid pressure brakes and magnetic track brakes, a retardation controller device for controlling one of said brake systems, and being normally adjusted to permit a predeterminedrate of retardation of the vehicle, and electrically controlled meansoperative in response to operation of said automatic means for adjusting said retardation controller device to permit a higher rate of retardation.

'7. In a vehicle brake system, in combination, a fluid pressure brake system, amagnetic track brake system, straight air means operative to effect the operation of said fluid pressure brake system to= effect an application of the fluid pressure brakes, automatic means forV effecting the operation of both of said brake systems to effect an application of both the fluid pressure brakes and magnetic track brakes, a retardation controller device for controlling one of said brake systems, and being normally adjusted topermit a predetermined rate of retardation of the vehicle, and a magnet valve device operative in response to operation of said automatic means for effecting an adjustment of said retardation controller device to permit a higher rate of 'retardation of the vehicle.

8. In a train brake system, in combination, a fluid pressure brake system, a magnetic track brake system, control means operative to effect the operation of said uid pressure brake system only when effecting a service application of the brakes, and operative to effect concurrent operation of both the fluid pressure brake system .and the magnetic track brake system when `effecting an emergency application of the brakes, and. means responsive to the speed of the train and operative `at a low predetermined speed for effecting a release-operation of the magnetic track brake system only to effect a release of the magnetic track brakes.

9. In a vehicle brake system, in combination, a brake cylinder, a magnetic track brake device, control means operative when effecting a service application of the brakes for effecting a supply of fluid under pressure to said brake cylinder and-operative When effecting an emergency application of the brakes for effecting a supply of fluid under pressure to said brake cylinder and the energizati'on of said track brake device, a retardation controller device for controlling brake cylinder pressure, and speed controlled means for controlling the energization of said track brake device.

10. In a vehicle brake system, in combination, a brake cylinder, a magnetic track brake device, control means operative when effecting a service application of the brakes to effect a supply of fluid under pressure to said brake cylinder only, and operative when effecting an emergency application of the brakes to effect a supply of fluid under pressure to said brake cylinder and energization and lowering to a track rail of said track brake device, a retardation controller device for controlling brake cylinder pressure, and speed controlled means for controlling both the adjustment of said retardation controller device and the energization of said track brake device.

11. In a vehicle brake system, in combination, a fluid pressure brake system comprising a brake pipe, a magnetic track brake system, meansl for effecting an application of the magnetic track brakeV system, speed controlled means, and means controlled jointly by the speed controlled means and by the pressure in the brake pipe for controlling the duration of application of the magnetic track brake system.

12. In a vehicle brake system, in combination, a brake cylinder, a magnetic track brake device, a normally charged brake pipe, means operative upon a reduction of pressure in said brake pipe for effecting a supply of fiuid under pressure to said brake cylinder and the energization of said track brake device, means operative to deenergize said track brake device at a low vehicle speed, and means controlled by brake pipe pressure for controlling said last means.

13; In a vehicle brake system, in combination, a brake cylinder, a magnetic track brake device, a brake pipe, means operative upon an emergency reduction in brake pipe pressure for effecting a supply of fluid under pressure to said brake cylinder and the energization of said track brake device, means operated according to the speed of the vehicle and operative at a low predetermined speed to deenergize said track brake device, and a switch device operated as a result of said reduction in brake pipe pressure for rendering said last means effective in controlling the deenergization of said track brake device.

14. In a vehicle brake system, a magnetic track brake device, means for effecting the energization of said magnetic track brake device to effect an application of the brakes, speed controlled means, means operative responsive to the operation of said speed controlled means and effective at a low vehicle speed to deenergize said track brake device, a normally charged brake pipe, and means operative only upon a reduction of pressure in said brake pipe at an emergency rate for rendering said deenergizing means effective.

15. In. a vehicle brake system, in combination, a magnetic track brake device, a source of current supply-lmeansfor establishing a circuit from said source of supply to said magnetic track brake device, a switch device operative to open said i circuit, a generator operative to produce a voltage proportional to the speed of thevehicle, means responsive. to said voltage and operative when the voltage corresponds to a low Vehicle speed for efiectingcthe opening of said switch means, a normally charged brake pipe,v and means including a pneumatic switch device operative upon a reduction in brake pipe pressure to render said y last mentioned means effective.

16. In a vehicle brake system, in combination, an adjustable type retardation controller device operated according to the rate of retardation of the vehicle, said retardation controller device having contacts and being normally adjusted t limit the rate of retardation of the vehicle to a predetermined value, means controlled by said contacts for controlling the application of the brakes, speed controlled means, and means responsive to operation or" said speed controlled means at a relatively low vehicle speed for adjusting the setting of said retardation controller device.

17. In a vehicle brake system, in combination,

a retardation controller device operated according to the rate of retardation of the vehicle, means responsive to the operation of said retardation controller device for controlling the application of the brakes, an adjusting mechanism comprising an element subject to the pressure of fluid in a chamber for adjusting the response of said retardation controller device, a brake pipe, speed controlled means, and means controlled jointly by the pressure in said brake pipe `and said speed retardation of the train produced by the application of the 'brakes from exceeding a predetermined value, means operative to deenergize said track brake device `before fluid under pressure is released from said brake cylinder, said brake cylinder pressure being normally increased when said track brake device is deenergized so as to maintain a predetermined rate of retardation of the vehicle, and -means operable so long as the brake cylinder pressure is above a predetermined value for preventing an increase in brake cylinder pressure upon deenergization of said track brake device.

21. In a vehicle brake system, in combination, a brakecylinder, means for effecting a supply of iluid under pressure to said brake cylinder, means including a retardation controller device for varying brake cylinder pressure to prevent the rate of retardation of the vehicle from exceeding a predetermined value, a brake pipe, and means controlled jointly by brake pipe pressure and the pressure of fluid in the brake cylinder for modifying the effectiveness of said last mentioned means.

22. In a vehicle brake system, in combination, a brake cylinder, means for effecting a supply of fluid under pressure to said brake cylinder, a retardation controller device operated according to the rate of retardation of the vehicle, an electrically operated valve device responsive to the operation Iof said retardation controller device for closing communication to the brake cylinder, a brake pipe, speed controlled means, and means controlled jointly by said speed controlled means and the pressure of fluid in both the brake pipe controlled means for controlling the pressure of uid in said chamber,

18. In a vehicle brake system, in combination, a retardation controller device operated according to the rate of retardation of the vehicle, means controlled by the retardation controller i device for controlling the application of the brakes, an adjusting mechanism comprising a movable abutment subject to the pressure of fluid in a chamber for adjusting the response of said retardation controller device to the rate of retardation of the vehicle, a normally charged pipe, a device operated according to the speed of the vehicle, and means controlled jointly by the pressure of fluid in said pipe and the operation of said speed operated device for controlling the pressure of lluid in said chamber, and operable to vary the pressure in said chamber at a relatively low vehicle speed.

19. In a vehicle brake system, in combination, a brake cylinder, means for effecting a supply of fluid under pressure to said brake cylinder, a rei tardation controller device operated according to sure to said brake cylinder and the energization' of said track brake device, to effect an application of the brakes, a retardation controller device operated according to the rate of retardation of the vehicle, means responsive to the operation of said retardation controller device for varying brake cylinder pressure, to prevent the rate of and the brake cylinder for also controlling the operation of said electrically operated valve dev1ce.

23. In a train or vehicle brake system, in combination, a fluid pressure brake system, a magnetic track brake system, a generator, an engine for driving said generator, means operative upon effecting an application of the fluid pressure brake system for supplying current to the magnetic track brake system from said generator, and means operative upon supplying current to the magnetic track brake system for controlling the speed of operation of said engine.

24. In a train or vehicle brake system, in combination, a fluid pressure brake system, a magnetic track brake system, a generator, an engine for driving said generator, means operative upon effecting an application of the fluid pressure brake system for establishing two independent circuits, means associated With one of said circuits for controlling supply of current from said generator to said magnetic track brake system, and means associated with the other of said circuits for controlling the speed of operation of said engine.

25. In a train or vehicle brake system, in combination, a fluid pressure brake system, a magnetic track brake system, a generator, an engine for driving said generator, means operative upon effecting an application of the fluid pressure brake system for establishing two independent circuits, means associated with one of said circuits for controlling supply of current from said generator to said magnetic track brake system, and means associated with the other of said circuits for controlling the speed of operation of said engine, and operable to reduce the speed of said engine, and consequently that of said generator, before terminating the supply of electric current to said magnetic track brake system.

26. In a train or AVehicle brake system, in comau positiona'ble control element for controlling the bination, a uid pressure brake system, a magspeed, of said engine and hence the output of said netic track brake system, a generator, an engine generator, and means for correlating the posifor driving said generator, means operative upon tion of said control element with supply of cureffecting an application of the fluid pressure rentA to said magnetic track brake system. brake systeml for supplying current to the magnetic track brake system from said generator, ELLIS E. HEWI'IT. 

